Wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths. Dense Wavelength Division Multiplexing (DWDM) technology greatly expands network capacity over existing network infrastructures by allowing the simultaneous transmission of hundreds of wavelengths over a single fiber. DWDM transmission has been used in a variety of applications, including, but not limited to, long haul service provider networks, metro service provider networks, enterprise data center connectivity, and the like. While DWDM is used in transmission, different switching technologies can be used to direct input data to outputs at router nodes. WDM and DWDM are used interchangeable herein to refer to WDM, DWDM, or both.
Current switching technologies fall into either electronic switching or optical switching technologies, based on how data is processed in the router. Electronic switching technology, also known as electronic packet switching (EPS), converts DWDM optical signals to electronic signals, and processes data (usually in the form of packets) electronically. However, as the number of DWDM channels increases, the optical/electrical/optical (O/E/O) conversion required by electronic switching significantly adds cost to the overall system cost. For example, while it is technologically feasible to carry 512 wavelengths in a single optical fiber, it requires 512 O/E/O pairs in EPS routers to just terminate a single DWDM link. Optical switching technologies, on the other hand, allow DWDM channels to pass through a node optically, which greatly reduces the cost of deploying DWDM channels over existing network infrastructure by reducing the need for O/E/O pairs. Optical switching can be further divided into three technologies: Optical Circuit Switching (OCS), Optical Packet Switching (OPS), and Optical Burst Switching (OBS). Unfortunately, there is no single switching technology that can cost-effectively scale with the number of DWDM channels while meeting the diverse needs of heterogeneous applications.
From an application's perspective, Internet traffic is inherently heterogeneous, embracing all data generated by applications that differ greatly in nature (e.g., VoIP, Video-on-Demand (VoD), IPTV, 3G/WiMax, Virtual-Private-Network (VPN), 10 Gigabit Ethernet). Each of the switching technologies (EPS, OCS or OBS) advantages and disadvantages for different applications. Although optical switching technologies have advantages in scaling up DWDM systems, neither OCS nor OBS can switch at the packet level. However, fine packet level granularity is desirable when transporting short, latency sensitive messages. Even between the two optical switching technologies, OCS and OBS, it is difficult to determine which is best for all types of applications. While it is clear that OBS performs well for most bursty Internet traffic, OCS is more suitable for applications that require sustained, long-term full channel bandwidth use (i.e. 10 Gb/s and above). OCS is also a better fit for mission critical applications which cannot tolerate any data loss or variable delay. One can conceivably build separate networks using different switching technologies to meet respective needs of applications. However, for some applications, this implies a higher capital investment, more management issues, and less flexibility. Unfortunately, there is no single type of network that can best fit the need for all types of applications due to the varying characteristics of different types of messages within each application. Although attempts have been made to support specific applications in the network, none of them address the DWDM channel scaling issue.
Dense Wavelength Division Multiplexing (DWDM) multi-mode switching systems and methods overcome the above-mentioned limitations by offering a unified approach to DWDM-based communication networks. DWDM multi-mode switching systems and methods provide for the use of multiple switching technologies (e.g. EPS, OBS and OCS) in the same network, on the same router platform, and at the same time. Additionally, DWDM multi-mode switching systems and methods also allow wavelength conversion in the various switching modes. Further, DWDM multi-mode switching systems and methods allow individual DWDM channels in the optical fiber to be dynamically reconfigured in EPS, OCS, or OBS modes, and switched using corresponding switching technologies within a router. DWDM multi-mode switching systems and methods support a large number of DWDM channels cost effectively by maintaining a relatively small set of shared electronic switching ports. With such architecture, each DWDM channel can be individually reconfigured to a different switching mode based on the dynamic traffic load. For example, individual applications or individual types of messages within an application can choose the mode that best suits its need.